Imperial College Kidney and Transplant Institute, 9th Floor Commonwealth Bldg, Hammersmith Hospital Campus, Du Cane Road, London W12 0NN.
J Clin Rheumatol. 2012 Oct;18(7):336-40. doi: 10.1097/RHU.0b013e31826d2005.
Antineutrophil cytoplasm antibodies (ANCAs) are useful diagnostic markers in vasculitis. Historical data have suggested the combination of cytoplasmic (C-ANCA) staining with antibodies specific for proteinase 3 (PR3-ANCA) is 99% to 100% specific for granulomatosis with polyangiitis. We aimed to establish the frequency and associations of PR3-ANCA in patients without primary systemic vasculitis using current methods in our laboratory.
This was a retrospective review of all patients identified as C-and PR3-ANCA positive as determined by indirect immunofluorescence and Luminex testing, respectively, in our laboratory over a 6-month period.
One hundred ninety-four patients were positive for both C- and PR3-ANCA. One hundred seventy-five patients had primary ANCA-associated vasculitis (AAV). Nineteen patients (9.7%) were C- and PR3-ANCA positive but without AAV. Clinical associations included infections, other autoimmune disorders, and malignancy. PR3-ANCA titer ranged from 31 to 278 U/mL (reference range, 0-25 U/mL). Three patients became PR3-ANCA negative after treatment of associated conditions. One patient went on to develop AAV 6 months after the study period.
We detected a higher than expected frequency (9.7%) of "incidental" C- and PR3-ANCA. Several factors may be contributing, including the occurrence of ANCAs in other inflammatory states, the increased use of ANCA testing in unselected populations with low clinical suspicion of AAV, recent changes to detection methods for ANCA, and the probability that circulating ANCAs predate onset of clinical disease. Our data underscore the need to secure tissue diagnosis in AAV and to exclude other underlying conditions such as infection. In addition, patients with unexplained ANCAs should be followed up because they are at risk of developing disease over time.
抗中性粒细胞胞浆抗体（ANCA）是血管炎的有用诊断标志物。历史数据表明，细胞质（C-ANCA）染色与蛋白酶 3（PR3-ANCA）特异性抗体的结合对肉芽肿性多血管炎具有 99%至 100%的特异性。我们旨在使用我们实验室当前的方法确定没有原发性系统性血管炎的患者中 PR3-ANCA 的频率和相关性。
这是对我们实验室在 6 个月期间通过间接免疫荧光和 Luminex 检测分别确定为 C 和 PR3-ANCA 阳性的所有患者的回顾性分析。
194 名患者 C 和 PR3-ANCA 均为阳性。175 名患者患有原发性 ANCA 相关性血管炎（AAV）。19 名患者（9.7%）C 和 PR3-ANCA 阳性但没有 AAV。临床相关性包括感染、其他自身免疫性疾病和恶性肿瘤。PR3-ANCA 滴度范围为 31 至 278 U/mL（参考范围为 0 至 25 U/mL）。在治疗相关疾病后，有 3 名患者的 PR3-ANCA 转为阴性。1 名患者在研究期间后 6 个月发展为 AAV。
我们检测到高于预期的“偶发性”C 和 PR3-ANCA 频率（9.7%）。可能有几个因素在起作用，包括 ANCAs 在其他炎症状态下的发生、在临床怀疑 AAV 低的未选择人群中增加使用 ANCA 检测、ANCA 检测方法的最新变化，以及循环 ANCAs 可能在临床疾病发病前存在的可能性。我们的数据强调了在 AAV 中获得组织诊断的必要性，并排除感染等其他潜在疾病。此外，由于随着时间的推移，这些患者有发生疾病的风险，因此应对不明原因的 ANCAs 患者进行随访。
